Tool dressing fixture



Nov. 26,v 1946. E, A BROWN 2,411,709 y TOOL DRESSING FIXTURE I Filed Aug. 19, 1944 .#ffi f5.7.) 20% u 22j INVENTOIL FIP/15.57 A. BROWN.

By {MMP- ATTORNE YS Patented Nov. 2.6, 1946 Ernest A. Brown, Elyria, Ohio Application August 19. 1944,' serial No. 550,151

A1 Y s This invention relatesbroadly to grinding fixtures and more specifically to mechanism for controlling the oscillatory movement of drills and similar tools while forming the lip angle .and land margin clearances therein.

One of the objects of the invention is to provide a fixture for dressing or re-working end cutting tools of the type used in screw machines, to form'combination drills, counterbores or center drills therefrom, the fixture being designed to produce the proper lip clearance angle, land margin and land clearance in each stepped portion thereof. v

Another object of the yinvention is to provide a drillholder which is designed to facilitate production of land margins `oi? Various widths.'

Another object of the invention is to construct a fixture having demountable bushings therein which are mounted for ready removal to accommodate substitutive bushings of different size.

Another object of the invention is to provide a drill supporting xturewhich isadapted to develop relief ycontours of uniform' configuration and proper form when used by unskilled or inexperienced operators..

Further objects ofthe invention reside in the provision of a fixture whichis economic/ofmanufacture, sturdy ofgstructure and susceptible of use on grinding machines of various forms..

Other objects and advantages ymore or less ancillary to the foregoing and the manner in which all the various objects are realized will ap'- pear in the following description, which considered in connection with the accompanying drawing, sets forth the preferred embodiment of y the invention.

Referring to the drawing wherein the preferred embodiment of the invention is illustrated:

Fig. l is a view in perspective of the improved tool dressing fixture including a drill shown in its assembled relation therein;

Fig. 2 is a longitudinal section through the X- ture shown in Fig. 1;

having the cam therein for the development 'of the lip clearance in the tools; and

Fig. 8 is a view in perspective ofthe fixture and fragmentary portionvof a grinding machine, the illustration showing the operative relation of the xture, the tool or work piece, andthe grinding wheel.

`Referring first to Figs. 2 and 3, the fixture comprises a rectangular block I0 machinedwith ia' longitudinal kerf II in one side thereof and bored throughout its length for the reception of bushingsr I2 and I3 and rotatable, centrallyV disposed sleeve I 4. Thepsplit portion of the block is drilled and tapped to receive set screws Il which `:are provided'to accommodate the clamped're'tention ofthe bushings within'the'block. The block is further drilled and tapped for'set screws I5 which are .preferably formed with cylindrical vends I8 adapted for engagement in openings in the bushings and provided to prevent longitudinal movement thereof.

' The side wall of the sleeve I4 is drilled toureceive a: pin I9 that protrudes` inwardly in the bore and Vis coni'lg'ured for' slidingengagement within the flute of the cutter supported therein. Portions ofthe end walls of the sleeve are .machined to' form slots 20 and 2| fory the reception of the end portions of thumb screws 22 and 23 mounted in the block IU. The slots are designed to. permit limited rotative movement of the tool while grinding the land clearance and to arrest such movement and initiate a helical move- Ament of the tool through the action of the pin I'9 when the grinding Wheel reaches the point that denes the width of the land margin. One of the slots is formed a few thousandths of an inch longer than the other in order to facilitate the production of landsV of different width, either the screw 22 or 23 being engaged within the proper slot during such operation. When a tool or similar helical fluted cutter is rotated within the fixture the pin I9 will cause the rotation o1' the sleeve until the shoulder of the slottherein is brought into engagement with the thumb screw.

Fig 3 is a transverse Sectio-n taken on a' plane 45 Whereupon .the sleeve will cease to rotate and indicated by the line 3-3 in Fig. 2;

Fig. 4 is a transverse section through the lix-V ture illustrated in Fig. 1;

Fig. 5 is a longitudinal section through the fixture showing in dotted lines a helical fluted drill in place;

' Fig. 6 is a View in perspective of the sleeve ,employed to control the development of the land clearance and land margin in the tool;

Fig. 7 is a View in perspective of the bushing 2B of the cam'is equal to the width of the land 3 clearance in such a tool, for example, the dimension B in Fig. 7.

The block l0 may be clamped upon the platen of vthe grinding machine or mounted with the base 30 thereof upon the face of magnetic chuck of the type customarily used in such environs. In setting up the fixture the block is adjusted relative to the grinding Wheel so that the medial axis of the ltool to be ground Will lie in a plane common to the vertical axis ofy the grinding Wheel spindle and Wirthlthe end portion of the tco1-en gaged with" the 'circumferential face of the wheel.

In forming the stepped shoulders on the tool,

the feed may be effected by raising the knee 'of the machine and reciprocating the platenpjn the.

customary manner.

A collar 21 bored for engagement` with-the" shank of the tool to be dressed is providedfto; ef-

fect the lineal translation vof the tool during the lip clearance grinding operation. The-collar or follower is locked upon the tool with set screws `28 mounted ony thebodythereofi the, endlfwall ofthe collar being formed Vwith lugs .ZSljdesigned `forengagement"fWiththe cam 2A.y The rake or jlip y clearance 'is gforned by r-st mounting. the

kcollar "2,1 riporijtiie'` m01', 'adjstmg the bloei; 'reia- 1 tiveftoth grindingl Wheel lto 7the vpoint Yangleof the tool, rtractingthe thumb screws ZZ and ,23 tg facilitate ther free rotation of the troolnwithin x* the vbushings YI 2 and I3, bringing thelip; of-the i vcol''intofc'ontact With ;the grinding WheeLf then f jjv'vnilenoiqing jth'ejmggc into Contact Winn 1 the fcamn'i'vljbtating .andf simultaneously feeding ythe $901." ir'totlie grinding,wheel until the .stockfis ground 'away to `thefiill length `of the point. f

1 "Ifhe, foregoing p'rocedure comprehends the operations rell'iired in grinding, the `lip, clearance and land margin in end lcutting tools of the usual form.' f Iny `redressingV or reworkingv tools of 4stepped`diam1ete`rs such, for example, as combination or center drills, vas used in `screw machines, the several shouldered'steps inthe drllsare first circled ground to size, then each .Steppin turn is grounded to the proper point angle, lip clearance, landmargin. and land clearance inthe manner described above. Y., A f y.

Although the foregoing description is necessarily of a` detailed character, in. order'that the inventioninay be completely setlforth, it is to be understood that thexsrpecic terminology is. not f intended to be re'str1ctive.or confining, and that various rearrangements of parts and modications o f detail may beresorted to without vdeparting .from the scope4 or. spirit of the invention as; herein claimed, y -'I"c1aim:

"1. A grinding fixture for helical fluted cutf thereof forguidin'gf-land l su l :cam in `the 'end-'Wall`4 of one o'f""th'e bushingsl a :'.collar engageable With"'the"dril1 and's'aid'v camjto 25v.facilitate grinding'the lip clearancein thieldrijll,

having an4 elongatedopening therein, a pin in rsaid block disposed forengagenient within the opening in the sleeve to delimit the rotative movement thereof for grinding the land margin and a second pin in the sleeve arranged for engagelnenti with the flutes in the tool to elect the helical movement thereof for grinding the lland clearance.

clearance, land and land clearance in helical Vfiuted drills comprising a rectangular block bored throughout its length, bushings in each end pporting :a "i-drill, a

a sleeve havingza slot iritl'ieleridfwall there'f'in :saidv block,r alfpin '-inthe borev of said sleeve" and means in; said'A block to 'delimit-'the 'rotative move- ;Lment of saidvsleevelil- 7* a.: 3.1Af grinding fixture for iiuted 4drills comprisingra block having a' bor`-`theein, untably` supon the free end of one of said bushings, co'l'l'ars .for each size ."drilldemuntablyf-fsupported` on said bore iintermediatef said bushlngs;

al pin-"in 'said fsleeve adaptedrfor engagement 'with the filut'e in -the drill being 'groundffafpin irsaid 'bloclgfar- 'outwardly in ai'he'lical path,`a ollarf-adaptedor engagement With-said calmT and for'rclyemountable securem'ent on lthel-t'olgfA a 'sleeve"'mountd'for vrotative movement'infsaid hole, fmeans tdelimit therotation "thereof, and means/in l'saidsleeve to elect the helical Smove'ne'ntfof "said tool after `theyrotative movement offthe sleeve hasJ 

